SALT LAKE CITY -- (KSTU) -- Salt Lake City Police say a security guard has been booked into jail on a murder charge after he fatally shot a trespasser following an altercation in downtown Salt Lake City.

Police say 26-year-old Timothy R. Lutes has been booked into jail on one count of murder in the death of 54-year-old Thomas Stanfield.

Things began around 5:25 a.m. when Lutes encountered Stanfield while Stanfield was trespassing in a plaza near 140 East and 300 South, outside the Department of Workforce Services Building.

Police say Lutes told the man to leave and was shining a light on the man as they talked, which sparked a physical altercation.

"The altercation lasted for quite some time," said Sgt. Brandon Shearer of Salt Lake City Police. "At some point during the altercation, the victim in this case... started walking away from Mr. Lutes. Again Mr. Lutes engaged him, and at some point—as Stanfield again appeared to be walking away from him—shots were fired, striking Mr. Stanfield and killing him."